People for the Ethical Treatment of Animals demanded today that the San Diego-based Petco chain stop selling rodents as pets, citing the death of a 10-year-old boy from a rare bacterial infection that his family says he contracted from a rat purchased at a Petco store.

Pankey Family

This undated photo released by Gomez Trial Attorneys courtesy the Pankey family, shows Aidan Pankey and one of his pet rats. Lawyers representing the Pankey family have filed a lawsuit against Petco Animal Supplies Inc., saying Aidan died from rat-bite fever contracted from a male rat purchased at one of the national chain’s stores.

A letter from Daphna Nachminovitch, PETA’s senior vice president of cruelty investigations, to James Myers, the CEO of Petco Animal Supplies Inc. contends that suppliers keep mice and rats in crowded boxes, creating a breeding ground for disease.

A Petco representative did not immediately respond to a request for comment on the PETA letter, which was spurred by last week’s news that the June 2013 death of San Diego County resident Aidan Pankey was caused by a streptobacillus moniliformis infection, one of two bacteria that cause Rat Bite Fever.

According to a lawsuit filed by Pankey’s family against Petco, one month after getting the rat at Petco, the boy awoke to severe pain, fever and stomach problems. He died June 12.

According to the U.S. Centers for Disease Control and Prevention, humans can contract Rat Bite Fever from bites or scratches from infected rodents like rats, mice and gerbils; handling rodents with the disease, even without a bite or scratch; or consuming food or drink contaminated with the bacteria. It cannot be spread between people.

Rat Bite Fever is the result of two bacteria — streptobacillus moniliformis, which is common in North America, and its Asian variant, Spirillum minus, according to the CDC.

The agency says symptoms usually occur three to 10 days after exposure to an infected rodent, but can be delayed as long as three weeks.

Most rats do not show symptoms of the infections, making inspection and treatment “not practical,” according to a statement Petco issued last week.

In her letter, Nachminovitch said the Petco statement “makes clear that the responsible decision is to end rodent sales.” She contended that PETA has received complaints from employees and a customer who reported seeing sick or injured rats and mice at Petco stores.